The generic term "threaded fastener" broadly encompasses any device such as a bolt, screw, or nut, which has helical threads formed on at least a portion of its surface. The installation and removal of threaded fasteners is generally accomplished using a tool of appropriate size and shape to engage the head of the fastener, so that it may be rotated. Conventional fastener tools include screwdrivers and various types of wrenches, driven either manually or by a pneumatic or electric motor. Regardless of the type of fastener or tool used, a common problem relates to the damage of an adjacent surface resulting from contact by the tool. For example, a screwdriver may slip from the head of a screw, damaging the underlying surface into which the screw is being driven, due to a worn or improperly-shaped screwdriver blade, deformation of the fastener, or inadvertence. Scratches or gouges in the finish of a panel or other surface thus caused by the blade of a screwdriver during a manufacturing process may make it necessary to rework or scrap an item, which has only been damaged cosmetically by the tool.
Abrasion and scratching of a finished surface may also occur when the end of a socket wrench contacts the surface as it is turned during installation or removal of a bolt or a nut. Rotation of the end of the socket wrench against the surface may leave circular scratches in the finish around the fastener that are unacceptable in appearance. If the scratches extend through a protective coating of paint, exposing the underlying metal surface, they may create an increased likelihood of corrosion or oxidation. Rework costs to correct damage caused by tools in the above-described manner are significant, exceeding several millions of dollars per year.
Powered fastener tools, for example, socket wrenches used with pneumatic drives, can subject an operator's hand to potential injury when grasped loosely in one hand to guide or steady the tool in engagement with a fastener. In addition, since an operator must handle a fastener tool during its use, his hands are subject to potentially painful contact with the tool if it is extremely cold or hot as a result of ambient conditions or due to contact with and thermal conduction between hot or cold components, such as hot spark plugs or bolts. Consequently, it may be difficult for the operator to grasp and guide a socket wrench or other tool onto the head of the fastener, or uncomfortable to hold the tool in place while the fastener is rotated. Particularly under extreme cold conditions, the operator's fingers may become so numb due to contact with cold tools that even simple operations are difficult. In addition, vibration transmitted through a socket wrench from a powered driver as the spinning socket is loosely supported in the operator's hand can induce carpal tunnel syndrome, i.e., nerve damage in the hand/wrist area or otherwise cause discomfort to the operator.
Poor lighting in a work area often hampers selection of the proper size tool needed for a job. Thus, for example, an operator may be forced to pick up and closely examine several socket wrenches before finding the one that fits a particular bolt or nut. Sizing inscriptions on tools may become covered with dirt or grease, forcing a trial-and-error approach to choosing the correct size tool.
In consideration of these problems it is an object of this invention to protect an underlying surface from damage caused by contact with a fastener tool. A further object is to prevent a fastener tool from slipping from the head of a fastener and gouging or scratching an underlying adjacent surface. Yet a further object is to stabilize a fastener tool relative to the fastener with which it is used. These and other objects and advantages of the present invention will be apparent from the attached drawings and the Disclosure of the Preferred Embodiments, which follow below.